import numpy as np
import matplotlib.pyplot as plt

labels = ["基準", "新規顧客", "既存アップセル", "解約", "値引き", "最終"]
changes = np.array([300, 80, 40, -60, -30, 0])
cumulative = np.cumsum(np.insert(changes[1:-1], 0, changes[0]))

fig, ax = plt.subplots(figsize=(7, 4))

ax.bar(labels[0], changes[0], color="#64748b")
ax.bar(labels[1:-1], changes[1:-1], bottom=cumulative, color=np.where(changes[1:-1] >= 0, "#22c55e", "#f97316"))
ax.bar(labels[-1], cumulative[-1], color="#2563eb")

for x, y in zip(labels[:-1], np.append(cumulative, cumulative[-1])):
    ax.text(x, y + 10, f"{y:.0f}", ha="center", va="bottom")

ax.set_ylabel("売上（百万円）")
ax.set_title("売上増減要因のウォーターフォール")
ax.axhline(0, color="#9ca3af", linewidth=1)
ax.grid(axis="y", alpha=0.2)

fig.tight_layout()
fig.savefig("static/images/visualize/bar/waterfall.svg")